Process for the manufacture of guanidinic derivatives



Patented Mar. 26, 1940 PROCESS FOR THE MANUFACTURE OF GUANIDINIC DERIVATIVES,

Alessandro Beretta, Milan, Italy, 'assignor to Montecatini Societa Generale per, llndustrla Mineraria e Chimica, Milan, Italy, a corporation' of Italy No Drawing. Application February 20, 1937, Serial No. 126,943. In ItalyFebruary 29, 1936 1 Claim. ('01. 2 -565) It is already known that an arylbiguanide can be obtained by the fusionin the dry and at high temperatures of a mixture of dicyandiamide with an aromaticamine or with one of its derivates.

For example, orthotolylbiguanide is prepared by fusion in the dry of dicyandiamide with orthotoluidine hydrochloride. It has also been proposed,in order to keep the temperature of reaction low and so obtainan economic advantage,

10 to treat the same reagents in the wet in the presence of special solvents. The cost of the latter, however, renders that method of procedure not very convenient. i

-It has now been found that the same reaction may be carried out at relatively low temperatures,

even in an aqueous medium, when care istaken to ensure the presence of an -excess of acid. To i a given and constantly stirred quantity of water are added, approximately molecular proportions, the dicyandiamide and the aromatic amine or a derivative thereof. The whole is then heated and the acid (for examplahydrochlorio acid) is added, preferably slowly, and the heating is continued for a certain period of time.

The mass obtained is, after cooling, rendered alkaline; in this manner a white precipitate is obtained, composed of arylbiguanide, which is then filtered, washed and clrie Example 1.One hundred and twenty parts of dicyandiamide and 140 parts of orthotoluidine are added to 600 parts of water kept well stirred. The whole is heated to.80-85 C. and, during the space of an hour, 161 parts of hydrochloric acid 20/21 B. are added; afterwards, heating is conride are added to 500. parts'of Water; 1 the same system given in Example 1, parts of hydrochloric acid 2021 B. are then added and i the whole heated for eight hours at -85 C.:

after cooling,thewhite well-developed crystals (composed of orthotolylbiguanide hydrochlo- 15 'ride) are filtered out.

set free byadding a 25% caustic soda solution. I

tinued for eight hours. The reactional mass, after'cooling to 20-25- C., is rendered alkaline with parts of 25% caustic soda solution. After allowing to stand for a 'few hours, the

'white precipitate, composed of orthotolylbigua- '5 nide which forms is filtered, washed and dried. Its melting point is 142-144 0. H

Example 2.Eighty-five parts of dicyandiamide and 142, parts of orthotoluidine hydrochlo- The base is subsequently The process described produces very pure products and with an excellent yield; moreover, on account of' the relatively low temperature 20 employed, it is much more economical than the processes known so far.

,I claimzw,

A, process for the manufacture of orthotolylbiguanide. which comprises heating dicyandia- 25 mide in an aqueous medium with a compound selected from the groupv consisting of orthotoluidine and orthotoluidine hydrochloride, in the presence of .more hydrochloric acid than the amount required for neutralization, at a tem- 80 perature of approximately 80-85 0., and alkalizing the mass so formed after it cools, by treatment with an alkaline compound.

ALESSAN'DRO BERETTA.

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